micro-area analysis technique has been developed rapidly with the research progress of new theory and new laser, and is in-situ micro sampling technique realizing the micro-area analysis. Laser ablation technology is widely used because of fast analysis, high accuracy of analysis results, relatively low acquisition and analysis cost. The laser ablation technology is used in combination with quadrupole or high resolution plasma mass spectrometry to analyze the content of the main and trace elements of the sample and the composition of some isotopes, and is used in combination with the multiple collector plasma mass spectrometry to precisely analyze various isotopes of different types of samples. Therefore, micro-area analysis technique is widely used in the field of earth sciences, archaeological science, material science, bioscience, criminal investigation principle, etc.
The fundamental principle of laser ablation technology is that laser focuses on the position to be analyzed of the surface of the sample in the sample chamber to ablate by laser ablation system, the generated ablation particles are transferred to the plasma mass spectra by transmission pipe using carrier gas (usually helium) to be ionized and be analyzed, so that the content or isotopic composition of the sample is obtained.
Analysis of Pb isotope in the micro-area of samples zone provides specific information of samples, for example, in geosciences, it can be used to study the geological process experienced by the rock mass where the geological sample is located; in environmental science, it can be used to study the sources of environmental pollutants; in archeology science, it can be used to study samples of mineral source areas, etc., therefore, analysis of Pb isotopes of different samples in these studies by laser ablation plasma mass spectrometry is of great significance. However, because the carrier gas and support gas for plasma (Ar) contain trace amount of Hg, the presence of these Hg has seriously affected the accurate determination of 204Pb by micro-area analysis of Pb isotopes, and 204Pb belongs to the low abundance (ordinary Pb has four isotopes, 204Pb, 206Pb, 207Pb and 208Pb, respectively, with corresponding abundances of 1.4245%, 24.1447%, 22.0827%, 52.3481%, the Pb isotope ratio commonly used in this study refers to 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb), since the low abundance 204Pb that is interfered is in the denominator, trace amounts of Hg (204Hg interferes 204Pb analysis) can have a serious effect on the accuracy of Pb isotopes analysis. And some samples, such as chalcopyrite, pyrite, sphalerite, etc. in deposit studies, often contain higher levels of Hg, or some samples contain lower levels of Pb (less than 5 ppm), so that these samples can not be accurately analyzed in current Laser Ablation-inductively Coupled Plasma Mass Spectrometry (LA-ICPMS).